feat: allow covariant overrides in classes (backport #2324) (#2385)

# Backport This will backport the following commits from `main` to `maintenance/v5.8`: - [feat: allow covariant overrides in classes (#2324)](#2324) <!--- Backport version: 9.5.1 --> ### Questions ? Please refer to the [Backport tool documentation](https://github.com/sorenlouv/backport) Co-authored-by: Momo Kornher <kornherm@amazon.co.uk>

Author: aws-cdk-automation

src/assembler.ts

@@ -226,7 +226,7 @@ export class Assembler implements Emitter {
  jsiiVersion,
  bin: this.projectInfo.bin,
  fingerprint: '<TBD>',
- usedFeatures: this.usedFeatures.size > 0 ? Array.from(this.usedFeatures) : undefined,
+ usedFeatures: _assemblyFeatures(this.usedFeatures), // might be appended later
  };
 
  if (this.deprecatedRemover) {
@@ -249,6 +249,15 @@ export class Assembler implements Emitter {
 
  const validator = new Validator(this.projectInfo, assembly);
  const validationResult = validator.emit();
+
+ // Inject detected features
+ if (validationResult.usedFeatures) {
+ for (const item of validationResult.usedFeatures) {
+ this.usedFeatures.add(item);
+ }
+ assembly.usedFeatures = _assemblyFeatures(this.usedFeatures);
+ }
+
  if (!validationResult.emitSkipped) {
  const zipped = writeAssembly(this.projectInfo.projectRoot, _fingerprint(assembly), {
  compress: this.compressAssembly ?? false,
@@ -269,6 +278,10 @@ export class Assembler implements Emitter {
  this._afterEmit();
  }
 
+ function _assemblyFeatures(usedFeatures: Set<spec.JsiiFeature>): spec.JsiiFeature[] | undefined {
+ return usedFeatures.size > 0 ? Array.from(usedFeatures).sort() : undefined;
+ }
+
  function _loadReadme(this: Assembler) {
  // Search for `README.md` in a case-insensitive way
  const fileName = fs

src/helpers.ts

@@ -28,7 +28,7 @@ export type MultipleSourceFiles = {
 /**
  * Assembly features supported by this compiler
  */
-export const ASSEMBLY_FEATURES_SUPPORTED: spec.JsiiFeature[] = ['intersection-types'];
+export const ASSEMBLY_FEATURES_SUPPORTED: spec.JsiiFeature[] = ['intersection-types', 'class-covariant-overrides'];
 
 /**
  * Compile a piece of source and return the JSII assembly for it